The present invention relates generally to medical devices, systems and methods, and more particularly to small, low cost, portable infusion devices and methods that are useable to achieve precise, sophisticated, and programmable flow patterns for the delivery of therapeutic liquids to a mammalian patient.
Today, there are numerous diseases and other physical ailments that are treated by various medicines including pharmaceuticals, nutritional formulas, biologically derived or active agents, hormonal and gene based material and other substances in both solid or liquid form. In the delivery of these medicines, it is often desirable to bypass the digestive system of a mammalian patient to avoid degradation of the active ingredients caused by the catalytic enzymes in the digestive tract and liver. Delivery of a medicine other than by way of the intestines is known as parenteral delivery. Parenteral delivery of various drugs in liquid form is often desired to enhance the effect of the substance being delivered, insuring that the unaltered medicine reaches its intended site at a significant concentration. Also, undesired side effects associated with other routes of delivery, such as systemic toxicity, can potentially be avoided.
Often, a medicine may only be available in a liquid form, or the liquid version may have desirable characteristics that cannot be achieved with solid or pill form. Delivery of liquid medicines may best be accomplished by infusing directly into the cardiovascular system via veins or arteries, into the subcutaneous tissue or directly into organs, tumors, cavities, bones or other site specific locations within the body.
Parenteral delivery of liquid medicines into the body is often accomplished by administering bolus injections using a needle and reservoir, or continuously by gravity driven dispensers or transdermal patch technologies. Bolus injections often imperfectly match the clinical needs of the patient, and usually require larger individual doses than are desired at the specific time they are given. Continuous delivery of medicine through gravity feed systems compromise the patient""s mobility and lifestyle, and limit the therapy to simplistic flow rates and profiles. Transdermal patches have special requirements of the medicine being delivered, particularly as it relates to the molecular structure, and similar to gravity feed systems, the control of the drug administration is severely limited.
Ambulatory infusion pumps have been developed for delivering liquid medicaments to a patient. These infusion devices have the ability to offer sophisticated fluid delivery profiles accomplishing bolus requirements, continuous infusion and variable flow rate delivery. These infusion capabilities usually result in better efficacy of the drug and therapy and less toxicity to the patient""s system. An example of a use of an ambulatory infusion pump is for the delivery of insulin for the treatment of diabetes mellitus. These pumps can deliver insulin on a continuous basal basis as well as a bolus basis as is disclosed in U.S. Pat. No. 4,498,843 to Schneider et al.
The ambulatory pumps often work with a reservoir to contain the liquid medicine, such as a cartridge or reservoir, and use electromechanical pumping or metering technology to deliver the medication to the patient via tubing from the infusion device to a needle that is inserted transcutaneously, or through the skin of the patient. The devices allow control and programming via electromechanical buttons or switches located on the housing of the device, and accessed by the patient or clinician. The devices include visual feedback via text or graphic screens, such as liquid crystal displays known as LCD""s, and may include alert or warning lights and audio or vibration signals and alarms. The device can be worn in a harness or pocket or strapped to the body of the patient.
Currently available ambulatory infusion devices are expensive, difficult to program and prepare for infusion, and tend to be bulky, heavy and very fragile. Filling these devices can be difficult and require the patient to carry both the intended medication as well as filling accessories. The devices require specialized care, maintenance, and cleaning to assure proper functionality and safety for their intended long term use. Due to the high cost of existing devices, healthcare providers limit the patient populations approved to use the devices and therapies for which the devices can be used.
Clearly, therefore, there was a need for a programmable and adjustable infusion system that is precise and reliable and can offer clinicians and patients a small, low cost, light weight, simple to use alternative for parenteral delivery of liquid medicines.
In response, the applicant of the present application provided a small, low cost, light weight, easy to use device for delivering liquid medicines to a patient. The device, which is described in detail in co-pending U.S. application Ser. No. 09/943,992, filed on Aug. 31, 2001, includes an exit port, a dispenser for causing fluid from a reservoir to flow to the exit port, a local processor programmed to cause a flow of fluid to the exit port based on flow instructions from a separate, remote control device, and a wireless receiver connected to the local processor for receiving the flow instructions. To reduce the size, complexity and costs of the device, the device is provided with a housing that is free of user input components, such as a keypad, for providing flow instructions to the local processor.
What is still desired are new and improved devices for delivering fluid to a patient. Preferably, the fluid delivery devices will be simple in design, and inexpensive and easy to manufacture, in order to further reduce the size, complexity and costs of the devices, such that the devices lend themselves to being small and disposable in nature.
In response, the present invention provides a device for delivering fluid to a patient, including an exit port assembly adapted to connect to a transcutaneous patient access tool, and a dispenser including at least two laminated layers of material defining a passageway connected to the exit port assembly, and an expandable accumulator in fluid communication with the passageway for controlling fluid flow from a reservoir to the exit port assembly. The laminated construction provides many benefits including, but not limited to, simplifying the design and manufacturing of the device, and further reducing the size, complexity and costs of the device. The device of the present invention, therefore, lends itself to being small and disposable in nature.
According to one aspect of the present invention, at least one layer of the dispenser comprises a resilient diaphragm. According to another aspect, the at least two laminated layers of the dispenser further include a first layer and a second layer received against the first layer. The second and the first layers define the passageway connected to the exit port assembly, and the second layer includes an opening in fluid communication with the passageway. The resilient diaphragm is received on the second layer covering the opening, and a third layer is received over the diaphragm on the second layer. The third layer has an pulse chamber over the diaphragm and in alignment with the opening of the second layer, and a port in fluid communication with the pulse chamber.
According to another aspect, one of the second and the third layers defines a recess receiving the diaphragm, and wherein the recess has a depth about equal to a thickness of the diaphragm such that the diaphragm is secured in a substantially fluid-tight manner between the second and the third layers. Preferably, a length and a width of the recess are greater than a length and a width of the diaphragm in order to decrease required manufacturing tolerances of the dispenser.
According to an additional embodiment of the present invention, the at least two laminated layers include a first layer, and a second layer received against the first layer. The second and the first layers define the passageway connected to the exit port assembly. The second layer includes a surface facing away from the first layer and having a recess, and an opening providing fluid communication between the recess and the passageway defined by the first and the second layers. The resilient diaphragm is received on the second layer covering the recess to form the expandable accumulator.
According to one aspect, the device includes an actuator for pushing the diaphragm into the recess to reduce the volume of the accumulator. According to another aspect, the actuator comprises a rotatable cam.
According to another embodiment, a third layer is received against the diaphragm and has a bore aligned with the recess of the second layer, and the actuator comprises a piston slidingly received in the bore. According to one aspect, a magnetic coil is received in the third layer coaxial with the piston for biasing the piston against the diaphragm upon being electrified. According to another aspect, the dispenser includes multiple accumulators arranged sequentially with respect to the passageway, and magnetic coils and pistons associated with each accumulator.
According to another embodiment, a third layer is received against the diaphragm and has a bore aligned with the recess of the second layer, and a fourth layer is received against the third layer and has a bore aligned with the bore of the third layer, and a gas generator is received in the bore of the fourth layer for pressurizing the bore and biasing the piston against the diaphragm upon being actuated. According to one aspect, the dispenser includes multiple accumulators arranged sequentially with respect to the passageway, and gas generators and pistons associated with each accumulator.
According to a further embodiment, the dispenser includes a first layer having a surface defining a groove, with the diaphragm positioned against the surface of the first layer such that the diaphragm and the groove define the passageway connected to the exit port assembly. A second layer is received against the diaphragm and includes a recess separated from the passageway by the diaphragm, and the portion of the passageway opposite the recess comprises the expandable accumulator. An actuator is received in the recess of the second layer for pushing the diaphragm towards the first layer upon being actuated to reduce the volume of the accumulator. According to one aspect, the actuator comprises a piece of piezoelectric material arranged to push the diaphragm upon contracting. According to another aspect, the actuator comprises multiple pieces of piezoelectric material arranged sequentially with respect to the passageway within the recess.
Another embodiment includes a first layer received against a second layer, with the layers defining the passageway connected to the exit port assembly, and the second layer including a recess facing the first layer. The dispenser further includes a piston slidingly received in the recess of the second layer, such that the piston and the recess define the expandable accumulator. According to one aspect, a spring biases the piston towards the first layer. According to another aspect, a magnetic coil is received in the second layer coaxial with the piston for biasing the piston towards the first layer upon being electrified.
These aspects of the invention together with additional features and advantages thereof may best be understood by reference to the following detailed descriptions and examples taken in connection with the accompanying illustrated drawings.